Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 240339

Area Forecast Discussion
National Weather Service Billings MT
839 PM MST Fri Feb 23 2018

Weak/split upper trof remains over eastern MT, but mid level winds
are increasing in central MT ahead of strong northwesterly jet
along the Pacific coast. Lee side pressure gradients have
increased, but we have recently seen a brief pressure rise in
response to aforementioned weak trof, with another period of
pressure falls expected later tonight. It is later tonight when we
will see winds at Livingston, Big Timber and Nye (and to a lesser
extent Harlowton) increase. Orientation of gradient will become
more favorable over time, but do not see enough mid level flow to
get gusts up to advisory strength. That being said, still
expecting 50 mph gusts later tonight into Saturday morning. Winds
will decrease but remain gusty as mid levels become more unstable
tomorrow afternoon. All of that being said, it will otherwise be a
quiet night of weather, with increasing snow showers over the
western mountains as the upstream Pacific trof moves inland. Have
adjusted temperatures down a bit more in eastern valleys per
current observations...already near or below zero at Sheridan,
Forsyth, Hysham and Miles City. It will be a warmer night than the
past several nights though, warmest in our west of course with
the increased wind along the foothills. JKL


.SHORT TERM...valid for Sat and Sun...

Overall, quiet weather will continue into the weekend with no
significant snow expected. A series of upper lows and troughs will
move onto the Pacific northwest coast, then dig southeast into
the four corners area during the next several days, and this is
where the bulk of any precipitation will be situated. A few weak
disturbances will move across our forecast area through the
weekend bringing a slight snow shower chance with the best chance
coming Sunday and Sunday night, mainly for the Beartooth/Absaroka
Mountains and adjacent foothills.

The main impact in the short term will be the return for strong
gusty winds for the Upper Yellowstone and Stillwater Valleys
tonight into Saturday morning. Lee-side troughing will set up
along with tighter pressure gradients. Wind and model guidance
have decreased slightly for the possibility for advisory winds for
the Livingston to Nye area during this time. Confidence is high
for 50 mph gusts but somewhat lower for gusts of 60 mph. As of
now, gusts around 55 mph looke likely with a few higher gusts. As
a result, we will hold off on issuing any wind advisories for
those areas at this time. These strong gusty winds will cause
areas of blowing and drifting snow from Billings and areas
westward, especially for areas prone to drifting. A much better
chance for advisory winds for these areas arrives Sunday and
Sunday night. Confidence is much higher for this period and an
advisory will most likely be needed later this weekend.
Temperatures for the weekend will moderate slightly to around or
slightly above freezing. Hooley

.LONG TERM...valid for Mon...Tue...Wed...Thu...Fri...

Overall, the forecast is not tremendously active with a couple of
splitting systems moving through the area. This will translate
into below seasonal temperatures, with general troughiness still
in place, and low chance of snowfall. The mountains and the west
will have the best chance of getting snow through the week, with
the plains remaining mostly dry.

The first splitting system to move through Monday and Monday
night, with the vast majority of the energy getting buried to the
south into southern California. A weak northern trough will
provide enough ascent for low PoPs, but as stated above, these
PoPs will be mainly confined to the mountains and the west.

The next system swings into the northern Rockies late in the
week. There was inconsistency with this system on previous runs of
the ECMWF and GFS, but the models were coming closer to agreement
now. The trough cuts a low off over southeast Montana, which
would put the best chance of significant snowfall over northern
Montana. This will need to be monitored closely, as the GFS was
cutting the low off further south and lining up closer with the
ECMWF. Still looks to far north to be a significant weather maker
for southern Montana and northern Wyoming at this time. TWH



Surface high pressure departing the region will allow for
increasing winds along the foothills and adjacent plains overnight
into Saturday morning. Expect wind gusts to 45 kts at KLVM and
other favored locations. Blowing snow is possible with minor
reductions to visibility as far east as KBIL. Isolated snow
showers, with occasional obscurations, are expected over the
mountains. TWH/RMS



    Sat     Sun     Mon     Tue     Wed     Thu     Fri
BIL 013/033 015/036 019/033 010/034 014/036 014/035 014/034
    00/N    11/Q    22/J    11/U    11/B    11/B    11/B
LVM 015/029 019/035 020/032 009/035 015/037 016/038 018/038
    22/J    42/Q    33/J    21/N    22/J    22/J    22/J
HDN 000/031 008/035 016/033 007/032 010/033 010/033 010/034
    00/B    11/B    12/J    11/B    11/B    11/B    11/B
MLS 903/022 010/032 016/029 007/028 009/029 008/028 009/029
    00/B    11/B    11/B    10/U    11/B    11/B    11/B
4BQ 000/024 008/032 015/032 008/030 011/032 011/032 012/032
    00/B    11/B    11/B    11/B    11/B    11/B    10/B
BHK 001/021 010/032 016/030 007/028 010/029 008/029 010/029
    00/B    11/B    11/B    00/B    01/B    00/B    00/B
SHR 901/032 009/036 015/032 008/033 009/035 011/035 012/037
    00/B    21/B    12/J    21/B    11/B    11/B    11/B




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